Within the interacting boson model, an intrinsic state is defined, in terms of quadrupole shape variables, from which all eigenstates of the interacting boson model can be projected by appropriately averaging over these shape variables and the orientations of the intrinsic state. With this intrinsic state, an energy surface and a Bohr hamiltonian can be derived for any boson hamiltonian in terms of these quadrupole variables. © 1980.
Ginocchio, J. N., & Kirson, M. W. (1980). An intrinsic state for the interacting boson model and its relationship to the Bohr-Mottelson model. Nuclear Physics, Section A, 350(1–2), 31–60. https://doi.org/10.1016/0375-9474(80)90387-5